I. Field of the Invention
The present invention relates to a borescope or endoscope utilizing flexible optical fibers or rigid optical systems for observation of the inside of the body cavities or of pipes and tubes in industrial applications. Throughout this disclosure, the term "borescope" will be used in a collective sense to include the entire range of elongated flexible and rigid optical inspection systems, endoscopes, sigmoidoscopes, and the like, whether intended for medical or industrial applications or for some other purpose.
II. Description of the Prior Art
Borescopes are commonly used for inspection of the human colon and urethra, and specifically, have been conventionally used in the diagnosis of tumors and other conditions in the lower gastrointestinal tract. The borescope examination involves the physician observing the intestinal wall through an eyepiece in the control head of the instrument. Generally, the borescope is provided with a source of illumination at its objective end, the end which is placed adjacent the area to be examined, and a bundle of light-transmitting fibers through which an image of the examined area is transmitted back to the eyepiece. The borescope can further incorporate a channel which provides a washing fluid for application to the site under examination as well as a surgical tip and other features.
Borescopes now available for medical purposes are also employed for observing the inside of a stomach, esophagus, and the like and can be classified into two typical types. One is the forward viewing type for observation along the longitudinal axis of the instrument at the distal end of the borescope and the other is the side viewing type for observation in one direction which is at a right angle or at some other angle relative to a longitudinal axis of the instrument at its distal end.
These two types have advantages and disadvantages, respectively. For example, in a narrow tubular region such as the esophagus, it is sometimes very difficult to use the side viewing type borescope because the site for observation is narrow and, moreover, it is difficult to provide a sufficient optical length between the lens and the object being inspected. Also, with a side viewing only type of borescope, one cannot see where one is transversing (that is, one cannot see in the same direction one is moving). Therefore, in such narrow tubular positions, forward-viewing type borescopes are generally used. On the other hand, in a wide bag-like cavity such a stomach, side viewing type borescopes are generally used because it is possible to observe all over the side walls.
For such reasons, the side viewing type borescope and the forward viewing type borescope are used for different applications according to the characteristics of the portion to be observed so that their respective advantages can be fully utilized. For example, when it is required to observe the esophagus and stomach of one patient at the same time, it is necessary to use two borescopes for the above reason. That is, the forward viewing type borescope is inserted for observing the esophagus at first and, after that, it is withdrawn and the side-viewing type borescope is inserted for observing the stomach. As a result, it takes a long time for observation. Moreover, as is widely known, pain of the patient is extremely pronounced when the hard distal end of the borescope passes his throat. Therefore, it is not desirable to insert two different borescopes successively because the pain of the patient will be further increased.
A factor to be considered in the construction of the borescope for its normal medical use is its flexibility and articulation which permits the objective tip to be directed along the channel of the colon, for example. A borescope can be made to traverse a considerable distance within the colon providing that any bends in the colon have a sufficiently large radius of curvature to enable the objective end of the borescope to be readily articulated to follow the course of the colon. Care must be taken, however, to precisely guide the instrument so as not to puncture the colon wall, especially as the device is being inserted.
Elongated tubular inspection devices, particularly such devices incorporating flexible fiber optics, are often used to inspect sites other than the internal organs of the human body which would not normally be visible to the human eye. The jet engine is one type of mechanical structure for which such inspection would be most useful, particularly, to inspect the first stage, or high temperature stage, of the engine just behind the burner can which has components that are most subject to wear and deterioration. The arrangement of the jet engine's rotor and stator blades, particularly those in the high temperature stage of the engine, presents a most complex geometry which has not been amenable to inspection in the past other than by first disassembling the engine. There has been a need for some form of inspection device which can be placed near the rotor and stator blades, and other important sites within the engine, for the inspection thereof without the laborious task of disabling the engine. The use of this type of instrument would effect a substantial savings in the cost of maintenance of the engines. Economy would result from the man-hours saved by avoiding the disassembly and reassembly of the engine. Additional economy would result from the increase in service time of the engine since the down time for maintenance would be substantially reduced.
While a jet engine has substantial regions of narrow channels and closed in spaces of the nature of the human colon or esophagus, it has an interior characterized by relatively open spaces more nearly of the nature of the human stomach. Hence it is most desirable for an industrial inspection system, as well as a medical inspection system, to have both forward viewing and side viewing capability. It would also be desirable for the system to be able to achieve this transition without time delay and without need for excessive manipulation of the system.
Although such devices currently exist, they are generally of a complex construction. This fact results, in a high initial cost plus substantial on-going expenses caused by the need for continuous maintenance. Also, some devices with interchangeable parts increase the probability of lost parts within the areas being viewed. It was with knowledge of the current state of the art that the present invention was conceived and has now been reduced to practice.